The present invention relates to a novel family of compositions based on alkyl polyglycosides and fatty alcohols, and to the use of these compositions for the preparation of emulsions.
Alkyl glycosides or alkyl polyglycosides (APG) are well-known non-ionic surface-active compounds which can be used on their own, or in association with other surfactants, in a broad range of industrial applications and especially in the cosmetics sector.
Alkyl polyglycosides were first used as foaming agents and, in this application, those with an alkyl chain containing from 8 to 14 carbon atoms were found to be of particular value.
More recently, alkyl polyglycosides have been used as emulsifiers and, in this application, those with an alkyl chain containing from 16 to 18 carbon atoms have proved to be of particular value.
Patent application WO 92/06778, in the name of the Applicant, describes for the first time the use of mixtures of alkyl polyglycosides and fatty alcohols as self-emulsifying agents.
More precisely, the mixtures described in said prior art document comprise:
from 60 to 90% by weight of at least one fatty alcohol having from 12 to 22 carbon atoms and preferably from 16 to 18 carbon atoms; and
from 10 to 40% by weight of an alkyl polyglycoside whose alkyl moiety is preferably identical to that of the fatty alcohol.
In Example 2, said document describes the use of a self-emulsifiable composition essentially consisting of alkyl polyglycosides and alcohols having 16 and 18 atoms.
The self-emulsifiable compositions described in the patent application cited above are marketed under the name Montanov(copyright) 68 and contain a mixture of alkyl polyglycosides whose fatty chains contain 16 and 18 carbon atoms, and a mixture of fatty alcohols with the same length of fatty chains.
Furthermore, patent application WO 95/13863, in the name of the Applicant, describes compositions, also based on alkyl polyglycosides and fatty alcohols, which are in the form of concentrates useful especially for the preparation of fluid emulsions.
These compositions essentially comprise a mixture of at least two alkyl polyglycosides which differ in the nature of their alkyl moiety.
It is specified that at least one of these alkyl polyglycosides contains an alkyl chain having from 16 to 22 carbon atoms and preferably from 16 to 18 carbon atoms.
It is also specified that the alkyl polyglycosides containing an alkyl chain having from 16 to 22 carbon atoms must represent at least 25% of the mixture of alkyl polyglycosides, and in all the Examples these alkyl polyglycosides contain 16 or 18 carbon atoms and represent at least 50% by weight of the mixture of alkyl polyglycosides.
Furthermore, patent application WO 96/37285, in the name of the Applicant, also describes compositions based on alkyl polyglycosides and fatty alcohols; these are useful especially for obtaining emulsions stable at low temperatures, for example at temperatures below xe2x88x9220xc2x0 C.
These compositions essentially comprise a mixture of at least three alkyl polyglycosides which differ in the nature of their alkyl moiety.
This mixture only contains alkyl polyglycosides having 12, 14, 16 or 18 carbon atoms, it being specified that the alkyl polyglycosides having 16 and 18 carbon atoms must be present in this mixture in an amount of at least 20% by weight, based on the total weight of the mixture of alkyl polyglycosides.
In all the Examples, the alkyl polyglycosides having 16 and 18 carbon atoms represent more than 60% by weight of the mixture of alkyl polyglycosides.
Thus the compositions based on alkyl polyglycosides and fatty alcohols which have been used hitherto in the state of the art for the preparation of emulsions are essentially characterized by the presence, in the mixture of alkyl polyglycosides, of a relatively large proportion, generally in excess of about 50% by weight, of alkyl polyglycosides whose alkyl moiety has from 16 to 18 carbon atoms.
Although such compositions are perfectly satisfactory, especially in terms of the stability of the emulsions obtainable therewith, it has been observed that these emulsions are not entirely satisfactory from the point of view of their texture, and particularly with regard to sensory evaluation criteria such as ease of spreading, evanescence, absorption by the skin, and the presence of residues after spreading.
Under these conditions, the object of the present invention is to solve the technical problem which consists in providing novel compositions for the preparation of emulsions whose textural properties are significantly improved by comparison with those of the emulsions obtained from the compositions described in the state of the art, the content of which was referred to above.
The solution to this technical problem, according to the present invention, consists of novel compositions based on alkyl polyglycosides and fatty alcohols, comprising:
5 to 60% by weight of a mixture of alkyl polyglycosides essentially consisting of:
0 to 20% by weight of at least one alkyl polyglycoside of formula (I):
R1O(G1)x1xe2x80x83xe2x80x83(I)
xe2x80x83in which R1 is a linear or branched aliphatic radical having 16 or 18 carbon atoms, G1 is a saccharide residue and x1 is between 1 and 5;
0 to 100% by weight of an alkyl polyglycoside of formula (II):
R2O(G2)x2xe2x80x83xe2x80x83(II)
xe2x80x83in which R2 is a linear or branched aliphatic radical having 14 carbon atoms, G2 is a saccharide residue and x2 is between 1 and 5; and
0 to 100% by weight of at least one alkyl polyglycoside of formula (III):
R3O(G3)x3xe2x80x83xe2x80x83(III)
xe2x80x83in which R3 is a linear or branched aliphatic radical having 20 or 22 carbon atoms, G3 is a saccharide residue and x3 is between 1 and 5; and
95 to 40% by weight of one or more alcohols of the formula Rxe2x80x2OH, in which Rxe2x80x2 is a linear or branched aliphatic radical having from 14 to 22 carbon atoms, and preferably of a mixture consisting of alcohols whose alkyl moiety is identical to the alkyl moiety R1, R2 and R3 of the above-mentioned alkyl polyglycosides.
Advantageously the above-mentioned mixture of alcohols essentially consists of:
0 to 20% by weight of at least one alcohol having 16 to 18 carbon atoms;
0 to 100% by weight of at least one alcohol having 14 carbon atoms; and
0 to 100% by weight of at least one alcohol having 20 to 22 carbon atoms.
Such compositions based on alkyl polyglycosides and fatty alcohols therefore differ essentially from the compositions of the state of the art in their relatively limited content of alkyl polyglycosides whose alkyl moiety contains 16 or 18 carbon atoms.
It has been discovered, totally surprisingly and unexpectedly, that such compositions make it possible to obtain emulsions with remarkable textural properties which are of particular value for their uses in the cosmetics sector.
A first preferred subfamily of compositions based on alkyl polyglycosides and fatty alcohols which can be used within the framework of the present invention consists of compositions in which the above-mentioned mixture of alkyl polyglycosides essentially consists of:
0 to 20% and preferably 0 to 15% by weight of at least one alkyl polyglycoside of formula (I) as defined above;
0 to 40% by weight of an alkyl polyglycoside of formula (II) as defined above; and
50 to 100% by weight of at least one alkyl polyglycoside of formula (III) as defined above.
A second preferred subfamily of compositions based on alkyl polyglycosides and fatty alcohols which can advantageously be used within the framework of the present invention consists of compositions in which the above-mentioned mixture of alkyl polyglycosides essentially consists of:
0 to 20% and preferably 0 to 15% by weight of at least one alkyl polyglycoside of formula (I) as defined above;
70 to 100% and preferably 90 to 100% by weight of an alkyl polyglycoside of formula (II) as defined above; and
0 to 30% and preferably 0 to 10% by weight of at least one alkyl polyglycoside of formula (III) as defined above.
The particularly preferred compositions within the framework of the present invention are those comprising: either:
8 to 40% by weight and preferably 8 to 30% by weight of the above-mentioned mixture of alkyl polyglycosides; and
92 to 60% by weight and preferably 92 to 70% by weight of one or more of the above-mentioned alcohols; or:
10 to 30% by weight and preferably 25% by weight of an alkyl polyglycoside of formula (II); and
90 to 70% by weight of an alcohol having 14 carbon atoms; or:
8 to 25% by weight and preferably 8 to 18% by weight of a mixture of alkyl polyglycosides essentially consisting of:
0 to 15% by weight of at least one alkyl polyglycoside of formula (I) as defined above;
0 to 25% by weight of an alkyl polyglycoside of formula (II) as defined in claim 1; and
75 to 100% by weight of at least one alkyl polyglycoside of formula (III) as defined above; and
92 to 75% by weight and preferably 92 to 85% by weight of a mixture consisting of alcohols whose alkyl moiety is identical to the alkyl moiety R1, R2 and R3 of the above-mentioned alkyl polyglycosides; or:
10 to 20% by weight of a mixture of alkyl polyglycosides essentially consisting of:
20 to 40% by weight and preferably about 30% by weight of an alkyl polyglycoside of formula (II) as defined above; and
60 to 80% by weight and preferably about 70% by weight of at least one alkyl polyglycoside of formula (III) as defined above, preferably an alkyl polyglycoside having 20 carbon atoms; and
80 to 90% by weight of a mixture consisting of alcohols whose alkyl moiety is identical to the alkyl moiety R2 and R3 of the above-mentioned alkyl polyglycosides.
As the saccharide residue represented respectively by G1, G2 and G3, the above-mentioned alkyl polyglycosides of formulae (I), (II) and (III) can contain a residue of glucose or dextrose, sucrose, fructose, galactose, maltose, maltotriose, lactose, cellobiose, mannose, ribose, dextran, talose, allose, xylose, levoglucosan, cellulose or starch.
Advantageously G1, G2 and G3 are each a glucose residue.
It should also be noted that each unit of the polyoside moiety of the alkyl polyglycoside can be in the xcex1 or xcex2 anomeric form and in the L or D form, and the configuration of the saccharide residue can be of the furanoside or pyranoside type.
The indices x1, x2 and x3 represent the mean degree of polymerization of the saccharide residue. These indices will preferably represent a number between 1.05 and 2.5 and particularly preferably between 1.1 and 2.
The expression xe2x80x9calkyl polyglycosidexe2x80x9d used within the framework of the present invention therefore arbitrarily denotes alkyl monoosides (degree of polymerization equal to 1) or alkyl polyglycosides (degree of polymerization greater than 1).
The alkyl polyglycosides of formulae (I), (II) and (III) are compounds whose alkyl radicals have chains of determinate length. However, these compounds can also contain minor proportions of compounds of the same type whose alkyl radicals have a longer and/or shorter chain, such compounds originating especially from the fatty alcohols, generally of natural or synthetic origin, used as starting materials for the synthesis of these alkyl polyglycosides.
The expression xe2x80x9cessentially consisting ofxe2x80x9d, used within the framework of the present patent application and the claims in order to characterize the above-mentioned mixture of alkyl polyglycosides, must therefore be understood not to exclude the presence, in the mixture of alkyl polyglycosides, of compounds whose alkyl radicals have 10, 12 or 24 carbon atoms, in a maximum cumulative amount of 10% by weight and preferably 5% by weight, based on the total weight of the mixture of alkyl polyglycosides.
The compositions according to the present invention based on alkyl polyglycosides and fatty alcohols can be prepared simply by mixing their constituents in desired predetermined proportions.
On the industrial scale they will preferably be prepared by one of the two methods conventionally used for the synthesis of alkyl polyglycosides, for example by reacting a fatty alcohol with a saccharide containing an anomeric OH, such as glucose or dextrose, in an acid medium.
Such methods of synthesis are well known and have been described in numerous documents, particularly in the Applicant""s documents referred to above.
If necessary, this synthesis may be completed with operations involving neutralization, filtration, partial distillation of the excess fatty alcohol, or decolorization.
The compositions according to the present invention based on alkyl polyglycosides and fatty alcohols can be used as the main emulsifier for the preparation of a variety of emulsions.
Thus, according to a second aspect, the present patent application aims to cover emulsions comprising at least an aqueous phase and an oily phase and, as the main emulsifier, a composition based on alkyl polyglycosides and fatty alcohols, as defined above.
In general terms, such an emulsion will comprise from 1 to 25% by weight and preferably from 1 to 10% by weight of the above-mentioned emulsifying composition.
The oily phase forming part of the emulsion can consist of the fatty alcohol or fatty alcohols forming part of the emulsifying composition of the invention, without it being necessary to use another oil. More generally, however, an oil selected from the following will be used:
oils of vegetable origin, such as sweet-almond oil, copra oil, castor oil, jojoba oil, olive oil, colza oil, groundnut oil, sunflower oil, wheat germ oil, maize germ oil, soya oil, cottonseed oil, lucerne oil, poppy oil, pumpkin oil, evening primrose oil, millet oil, barley oil, rye oil, safflower oil, candlenut oil, passiflora oil, hazelnut oil, palm oil, shea butter, apricot kernel oil, calophyllum oil, sysymbrium oil and avocado oil;
modified vegetable oils such as the products known by the INCI names Apricot Kernel Oil PEG-6 esters and Olive Oil PEG-6 esters;
oils of natural origin, such as perhydrosqualene and squalene;
mineral oils such as paraffin oil or vaseline oil; and mineral oils originating especially from petroleum cuts, such as isoparaffins with boiling points of between 300 and 400xc2x0 C.; and
synthetic oils, especially fatty acid esters such as butyl myristate, propyl myristate, cetyl myristate, isopropyl palmitate, butyl stearate, hexadecyl stearate, isopropyl stearate, octyl stearate, isocetyl stearate, dodecyl oleate, hexyl laurate and propylene glycol dicaprylate; esters derived from lanolic acid, such as isopropyl lanolate and isocetyl lanolate; triglycerides such as glycerol triheptanoate; alkyl benzoates; isoparaffins; polyalphaolefins; polyolefins; synthetic isoalkanes such as isohexadecane and isododecane; and silicone oils. Among the latter, there may be mentioned more particularly dimethylpolysiloxanes, methylphenylpolysiloxanes, silicones modified by amines, silicones modified by fatty acids, silicones modified by alcohols, silicones modified by alcohols and fatty acids, silicones modified by polyether groups, epoxy-modified silicones, silicones modified by fluorinated groups, cyclic silicones and silicones modified by alkyl groups.
In general terms, the emulsions according to the present invention will comprise up to 50% by weight of oily phase as defined above.
These emulsions can be prepared simply by dispersing a fatty phase, consisting of the above-mentioned emulsifying composition and optionally one or more oils as described above, in a hydrophilic phase, generally water or a hydrophilic solvent.
The dispersion process can be carried out hot or cold, depending on the melting point of the emulsifying composition, it being necessary for all the constituents to be liquid at the time of mixing.
The emulsions obtained in this way differ from those which can be obtained from the emulsifying compositions of the state of the art in that they have remarkable textural properties and sensory characteristics, as will be demonstrated below.
These emulsions can also comprise a complementary emulsifier in an amount such that the total amount of emulsifiers in the emulsion is less than or equal to 25% by weight.
It has in fact been found, surprisingly, that the emulsifying compositions according to the present invention based on alkyl polyglycosides and fatty alcohols potentiate the emulsifying properties of a number of traditional emulsifiers, particularly those of non-ionic or anionic type, while at the same time conferring remarkable textural properties and sensory characteristics on the emulsions obtained from these mixtures of emulsifiers.
A non-ionic complementary emulsifier can be for example an ethoxylated alcohol, an ethoxylated fatty acid, a glycerol ester, an ethoxylated glycerol ester, a sorbitan ester, a polysorbate, a polyglycerol ester, a sucrose ester, an alkyl glucose ester, an ethoxylated alkyl glucose ester or a dimethicone copolyol.
An anionic complementary emulsifier can be for example an alkylsulfate, an alkylphosphate, a phosphated ethoxylated alcohol, a sulfated ethoxylated alcohol, a fatty acid soap, an acylate or a dimethicone copolyol phosphate.
The emulsifying compositions according to the present invention based on alkyl polyglycosides and fatty alcohols can also be used for the preparation of fluid emulsions. In this case, a particular complementary emulsifier or co-emulsifier, selected from ethoxylated vegetable oils and ethoxylated methyl esters of vegetable oils, will be used.
In general terms, the total amount of emulsifiers in the emulsion will be less than or equal to 25% by weight and the weight ratio of the main emulsifier, consisting of the mixture of alkyl polyglycosides and fatty alcohols, to the co-emulsifier will be between 98:2 and 20:80.
It has in fact been discovered, totally unexpectedly, that in contrast to the compositions of the state of the art based on alkyl polyglycosides and fatty alcohols, these novel emulsifying compositions of the invention, when associated with a secondary emulsifier selected from ethoxylated vegetable oils and ethoxylated methyl esters of vegetable oils, make it possible to formulate fluid emulsions whose viscosity depends little on the nature of the emulsified oil; this applies to a very wide diversity of oils, without it being necessary in each case to adjust the ratio of the composition based on alkyl polyglycosides and fatty alcohols (main emulsifier) to the secondary emulsifier.
An ethoxylated vegetable oil which can be used within the framework of the invention can be for example an ethoxylated maize oil, an ethoxylated apricot kernel oil, an ethoxylated sunflower oil, an ethoxylated colza oil, an ethoxylated jojoba oil, an ethoxylated grapeseed oil or an ethoxylated linseed oil.
An ethoxylated methyl ester of a vegetable oil can be for example an ethoxylated methyl ester of maize oil, an ethoxylated methyl ester of sunflower oil, an ethoxylated methyl ester of colza or an ethoxylated methyl ester of linseed.
It has furthermore been discovered, totally unexpectedly, that the emulsifying compositions of the invention, when associated with one or more alkyl polyglycosides having 8 to 12 carbon atoms (forming a co-surfactant), make it possible to formulate fluid emulsions whose viscosity depends little on the nature of the emulsified oil; this applies to a very wide diversity of oils, without it being necessary in each case to adjust the ratio of the composition based on alkyl polyglycosides and fatty alcohols to the co-surfactant.
Thus the present invention covers emulsions which also comprise a co-surfactant selected from alkyl polyglycosides having from 8 to 12 carbon atoms, in an amount such that the total amount of emulsifier and co-surfactant is less than or equal to 25% by weight, the weight ratio of the emulsifier to the above-mentioned co-surfactant being between 99:1 and 60:40.
The surfactant is advantageously an alkyl polyglycoside having 12 carbon atoms.
The emulsions obtained within the framework of the present invention (with or without complementary emulsifiers) are generally stable for at least 24 h at room temperature.
It has also been found that the stability of these emulsions can be considerably enhanced by adding to the emulsion synthetic polymers or natural hydrocolloids normally used in cosmetics.
Such agents capable of enhancing the stability of the emulsions will generally be used in an amount of about 0.1 to 5% by weight, based on the weight of the emulsion.
The polymers and hydrocolloids which can be used to stabilize the emulsions based on compositions according to the present invention of alkyl polyglycosides and fatty alcohols can be selected for example from:
crosslinked or non-crosslinked acrylic or methacrylic polymers and copolymers such as carbomer, acrylate/steareth-20 methacrylate copolymers, crosslinked acrylate/C10-30-alkyl acrylate polymers, polyglyceryl acrylate, polyglyceryl methacrylate and sodium polyacrylate;
polymers and copolymers derived from styrene or vinyl, such as sodium polystyrenesulfonate or a crosslinked PVM/MA(polyvinyl methyl ether/maleic anhydride)/decadiene polymer;
polymers and copolymers derived from acrylamide, such as the product known under the name polyacrylamide/C13-14-isoparaffin/laureth-7;
gums of natural origin, such as xanthan gum, sclerotium gum, alginates, carrageenates, glucomannans and karaya gum;
cellulosic polymers and derivatives thereof, such as microcrystalline cellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; and
mineral compounds such as bentonites, smectites and magnesium and/or aluminum silicates.